Abstract: A fuel supply system has a fuel injector positioned to directly inject fuel into a combustion chamber, and it is capable of performing a split injection wherein a first fuel injection in each engine cycle precedes a second fuel injection that occurs during compression stroke in the same engine cycle. A spark plug produces a spark to ignite a first air/fuel mixture portion created due to the second fuel injection, initiating a first stage combustion. The first stage combustion raises temperature and pressure high enough to cause auto-ignition of a second air/fuel mixture portion surrounding the first air-fuel mixture portion, initiating a second stage combustion.

Abstract: A direct fuel injection engine has a fuel injection valve that injects fuel toward a cavity formed in a top of a piston, and a spark plug that ignites the fuel-air mixture resulting from the fuel injection. The direct fuel injection engine is configured to strengthen the penetration of the fuel streams, to improve the directionality of the fuel streams and to form in the cavity an agglomerate fuel-air mixture that is homogeneous and has uniform concentration. The cavity preferably has a bottom surface, a curved surface, and a flat surface. The fuel injection valve has a plurality of injection vents that spray solid-core fuel streams with angles formed between adjacent injection vents that are less than or equal to the spray angle of the fuel stream sprayed from each injection vent. The fuel streams form a combined fuel stream having a hollow circular cone shape.

Abstract: A direct fuel injection engine has a fuel injection valve that injects fuel toward a cavity formed in a top of a piston, and a spark plug that ignites the fuel-air mixture resulting from the fuel injection. The direct fuel injection engine is configured to strengthen the penetration of the fuel streams, to improve the directionality of the fuel streams and to stably form an agglomerate fuel-air mixture close to the spark plug. The cavity preferably has a bottom surface, a curved surface, and a flat surface. In a plan view taken along the center axis of the engine cylinder, cavity C is shaped like an ellipse whose foci are located at the tip of fuel injection valve and the spark discharge gap of spark plug, respectively. The fuel injection valve has a plurality of injection vents that spray solid-core fuel streams.

Abstract: An internal combustion engine includes a cylinder including at least one intake valve which is selectively open to allow at least air to enter the cylinder and at least one exhaust valve which is selectively open to allow residual gas escape from the cylinder after a firing event. An auto-ignition system for such an engine comprises a device communicably coupled with the cylinder. The device is, effective to allow an amount of high temperature and pressure residual gas to enter the cylinder in the compression stroke of an engine cycle after valve closure of the intake valve.

Abstract: In a compression self-ignition gasoline internal combustion engine, a fuel injector through which a gasoline fuel is injected uninterruptedly within a combustion chamber of an engine cylinder is provided, a mixture of air and gasoline fuel within the combustion chamber is self-ignited through a compression action of a piston, an intake valve an open timing of the intake valve is set to a mid-way point through a suction stroke of the piston, a closure timing of an exhaust valve is set to a mid-way point through an exhaust stroke thereof, and gasoline fuel injection timing and quantity per combustion cycle injected through the fuel injector is controlled in such a manner that a first gasoline fuel injection is set during a minus valve overlap time interval during which both of exhaust and intake valves are closed and a second gasoline fuel injection is set during at least one of the suction stroke and the subsequent compression stroke.

Abstract: A system and method for controlling an internal combustion engine employs a split injection to create stratified air/fuel mixture charge. The stratified charge includes an ignitable air/fuel mixture portion around a spark plug within the surrounding lean air/fuel mixture and experiences a two-stage combustion. The first stage is combustion of the ignitable air/fuel mixture portion initiated by a spark produced by the spark plug, providing an additional increase of cylinder pressure. The second stage is auto-ignited combustion of the surrounding lean air/fuel mixture induced by such additional cylinder pressure increase. The system and method also employ generating a combustion event indicative (CEI) parameter related with combustion speed or ignition timing point of auto-ignition of auto-ignited combustion of the surrounding mixture, and determining control parameters of a spark timing controller and a fuel supply controller in response to the CEI parameter.

Abstract: A system and method for enhanced combustion control in an internal combustion engine is disclosed. A fuel supply system has a fuel injector positioned to directly inject fuel into a combustion chamber, and it is capable of performing a split injection wherein a first fuel injection in each engine cycle precedes a second fuel injection that occurs during compression stroke in the same engine cycle. A spark plug produces a spark to ignite a first air/fuel mixture portion created due to the second fuel injection, initiating a first stage combustion. The first stage combustion raises temperature and pressure high enough to cause auto-ignition of a second air/fuel mixture portion surrounding the first air-fuel mixture portion, initiating a second stage combustion. An engine controller is programmed to perform control over initiation timing of the second stage combustion in response to at least one of the engine speed and load.

Abstract: During operation with part load, a gasoline internal combustion engine is operated with a lean air/fuel mixture by auto-ignition. During operation with full load, spark-ignition is used to operate the engine. The internal combustion engine is operated in three auto-ignition combustion modes depending upon magnitude of a predetermined operating parameter. The operating parameter is indicative of the engine load or the engine speed. The three auto-ignition combustion modes are a gasoline reform auto-ignition combustion mode, an auto-ignition stratified charge combustion mode, and an auto-ignition homogeneous charge combustion mode. In the gasoline reform auto-ignition combustion mode that may be selected during operation with low part load, a first fuel injection during an exhaust gas retaining phase produces sufficient amount of active fuel radicals for promotion of auto-ignition of air/fuel mixture produced by a second fuel injection during the subsequent compression phase.

Abstract: A gasoline engine has an actuating system including an in-cylinder fuel injection system and an ignition system, capable of changing over combustion between spark ignition combustion and compression autoignition combustion, and a controlling system for controlling the combustion changeover. In a transition from one combustion to the other, the actuating system is controlled to perform transient combustion such as stratified charge combustion with fuel injection on the compression stroke, or combustion with fuel injection during a valve shutoff period during which intake and exhaust valves are both closed.

Abstract: A split injection of gasoline produces stratified charge in at least one cylinder. A sensor measures cylinder pressure or knock and generates a sensor signal indicative of combustion event timing of stratified charge. From the sensor signal, a controller determines an actual value of a characteristic parameter representing combustion event timing in the cylinder. The controller modifies at least one of operating variables governing a split injection for the subsequent cycle in such a direction as to decrease a deviation between the actual value of the characteristic parameter and a target value thereof toward zero.

Abstract: During operation with part load, a gasoline internal combustion engine is operated with a lean air/fuel mixture by auto-ignition. During operation with full load, spark-ignition is used to operate the engine. The internal combustion engine is operated in three auto-ignition combustion modes depending upon magnitude of a predetermined operating parameter. The operating parameter is indicative of the engine load or the engine speed. The three auto-ignition combustion modes are a gasoline reform auto-ignition combustion mode, an auto-ignition stratified charge combustion mode, and an auto-ignition homogeneous charge combustion mode. In the gasoline reform auto-ignition combustion mode that may be selected during operation with low part load, a first fuel injection during an exhaust gas retaining phase produces sufficient amount of active fuel radicals for promotion of auto-ignition of air/fuel mixture produced by a second fuel injection during the subsequent compression phase.

Abstract: Stroke cycles of a self-igniting gasoline engine (10) comprising an intake stroke, compression stroke, power stroke and exhaust stroke are performed sequentially by a piston (12), and self-ignition of the fuel mixture is performed by compression of the fuel mixture in the compression stroke. The strokes of the piston (12) are detected by a sensor (23), and an electronic control unit (1) controls a valve timing adjustment mechanism (15, 18) so that a sealed period occurs when both an exhaust valve (17) and intake valve (14) are closed in the vicinity of top dead center of the exhaust stroke. The electronic control unit (1) also controls the fuel injection timing of a fuel injector (19) so that fuel is injected into the combustion chamber (11) during the sealed period.

Abstract: An exhaust system for internal combustion engines includes at least two exhaust passages, each passage communicated with at least one branch exhaust passage of an exhaust manifold communicating exhaust ports of a multiple-cylinder engine, and a confluent exhaust passage disposed downstream of said at least two exhaust passages, said confluent exhaust passage including a confluent point for converging downstream ends of said at least two exhaust passages. The exhaust system also includes a communication passage substantially parallel with the at least two exhaust passages and a valve disposed in the communication passage, for allowing a portion of exhaust gas flow to bypass said confluent point only when the engine is within a predetermined high engine revolution range.

Abstract: To smoothly introduce intake air or mixture through at least one intake valve and exhaust combustion gas through at least exhaust valve, an intake side conical wall surface is formed in an inner wall of the cylinder head in smooth continuous connection with a conical surface formed at an end of the intake valve seat, and an exhaust side conical wall surface is also formed in the inner wall of the cylinder head in smooth continuous connection with a conical surface formed at an end surface of the exhaust valve seat. It is preferable not to allow liquid fuel introduced through the intake to flow directly toward an ignition plug provided at the center of the cylinder, but to allow the introduced liquid fuel to flow directly toward the exhaust port along a flat surface, recess, groove, guide surface, etc. formed around the ignition plug for prevention of misfiring.